Manitowoc QuietQube SD0672C Technician's Handbook page 159

Analyzing Suction Pressure
The suction pressure gradually drops throughout the
Freeze cycle. The actual suction pressure (and drop
rate) changes as the air and water temperature
entering the ice machine changes. These variables
also determine the Freeze cycle times.
To analyze and identify the proper suction pressure
drop throughout the Freeze cycle, compare the
published suction pressure to the published Freeze
cycle time.
NOTE: Analyze discharge pressure before analyzing
suction pressure. High or low discharge pressure may
be causing high or low suction pressure.
Step
1.Determine the ice machine operating conditions.
*Temperature of air entering the condenser. Look up and
determine the published suction pressure.
2.Perform an actual suction pressure check at the
beginning, middle and end of the Freeze cycle. *Freeze
cycle begins when the water pump starts
3.Compare the actual Freeze cycle suction pressure (step
2) to the published Freeze cycle pressure. Determine if the
suction pressure is high, low or normal.
Part Number 80-1505-3 6/11
Procedure
159